1. Department of Obstetrics and Gynecology, CHA Ilsan Medical Center, CHA University School of Medicine, Goyang-si, Republic of Korea
2. Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Republic of Korea
3. Department of Medical Science, Korea University Graduate School, Seoul, Republic of Korea
4. Department of Preventive Medicine, Korea University College of Medicine, Seoul, Republic of Korea